Staphylococcus aureus colonization and infection in newborn nursery patients

The correlation between Staphylococcus aureus colonization and infection among newborns was studied during a four-year period. Of the 9,423 newborns cultured, 24% were colonized at the time of discharge and in 2% of these an infection developed, whereas only 0.2% of the noncolonized newborns experienced a staphylococcal infection. The weekly colonization rates ranged from 0% to 62%, and outbreaks of infections (two or more concurrent) occurred periodically when the colonization rates ranged from 11% to 57%. Colonization rates per se did not serve as an indicator of an actual or potential outbreak of infection. Instead, the occurrence of two or more concurrent cases of staphylococcal infection or presumptive evidence of an outbreak seems to be a more reliable indicator than colonization monitoring.